I’m taking Olanzapine and it has caused me to rapidly gain weight. Do any other antipsychotic medications have the same benefits without weight gain.

POSSIBLY. Unfortunately this is one of the common side effects of many of the anti psychotic medications. Some of the newer ones may have less weight gain but ultimately you will need a healthy life style with eating healthy and exercise daily. It is possible to not gain weight or to lose weight but you will really have to work on it. Newer ones like Fanapt and Vraylar for instance.